Crime: Billings for exaggerated or nonexistent care increase from Mexico to Nigeria. FBI probes scams that sometimes lure patients in for a piece of the profit.

Fraud investigator Kennedy said a doctor hired to review out-of-state Medi-Cal claims first noticed the high number of bills from Guevara earlier this year. When investigators began interviewing patients, they found that few had spent more than a few hours in Guevara's tiny Tijuana clinic, he said.

Norma Hilding said she was shocked when investigators told her how much Guevara billed for treating her daughter's runny nose. Guevara also billed $2,340 for two days of hospitalization for examining her husband's back.

"It's unbelievable," said Hilding, 37, who has not been implicated in the alleged billing scheme. "We never stayed in any hospital."

Guevara also visited Medi-Cal recipients in Los Angeles and Riverside counties, then billed as if they had been hospitalized in his Tijuana clinic, Kennedy said.

"That's what got us, that he even came up here to see patients," Kennedy said.

Medi-Cal watchdog Jan Goldsmith, a Republican Assemblyman from Poway, said the Guevara case shows that foreign coverage is a loophole that needs to be closed. He said he plans to introduce legislation disallowing coverage outside the United States during the next legislative session.